A conventional aquarium pump as shown in FIGS. 1-4 comprises: a base portion 1 supporting on a table surface by a plurality of legs 3 having an outer extension 11 circumferentially formed on a bottom plate portion 10 of the base portion 1, and an inner extension 12 formed on the bottom plate portion 10 within the outer extension 11; an air-pumping means 4 connected with an air delivery box 5 shielded by an inner cover 6 mounted on the inner extension 12 as packed by a packing member 13; and an outer cover 7 provided with an adjusting knob 14 and an air inlet port 15 mounted on the outer extension 11 of the base portion 1. The air-pumping means 4 includes a pair of pumping diaphragms 41 reciprocatively compressed and released by a pair of actuating levers 42 resiliently secured to the box 5 each lever 42 having a magnet 421 secured on the lever 42 to be intermittently attracted by an electromagnet 43 electrically connected with a power source for pumping air outwardly through two discharge tubes 55 protruding outwardly beyond the two covers 6, 7 for delivering air into an aquarium.
However such a conventional aquarium pump still has the following drawbacks:
1. During the air-pumping operation by the pump, serious vibration of the air-pumping means 4 may exert noise by transmitting noise sound waves downwardly through the bottom plate 10 made of plastic material.
2. The use of legs 3 shaped as solid cylindrical stems of elastomeric material is not satisfactory for reducing noise.
3. Pumping air through two straight passages 5a formed in the base 5 (FIG. 4) and discharging outwardly directly does not slow down the transmission of the sound wave in box passages, thereby the aquarium pump is inefficient in preventing noise pollution.
It is therefore expected to disclose a silencer for improving a noise reduction for an aquarium pump.